@Miss_B Thank you! I see some of my assumptions were right. As of now I am (as much as one can be) certain that my site is secure and clear of malware. Before coming here I went through a many day process with a third party professional and my hosting provider (Site5) to ensure that the malware was cleared out and all my access points were updated.
What that means, is now I have a secured server, but with a bunch of holes blown in it from the malware passing through. The malware itself seemed to be overwriting php files. For instance, outside of my forum it was replacing the index.php and about.php in my main directory. It seemed to have crawled through the forum and done the same. So right now, I HOPE that I just need to repair the installation to solve the problem.
The hurdles in front of me are two fold and represent two paths forward as I understand after everyone's helpful advice here.
Option A: Get my hosting provider to help me get the necessary upgrades so that I can run PHP 8 and eventually upgrade my suite to the latest version with a manual install, hopefully repairing the installation in the process.
Option B: Find out what version I was running (and thus my database would be compatible with) and install that version manually to repair the files.
Option A is the cleanest, but honestly Site5 has not been very good to me over time (they bought out my previous hosting service and they were not an upgrade). I may need to move to a new hosting provider before I can get PHP 8 based on the service I have gotten from them thus far. Option B, if it would work, I think would get me to a solution faster for my community.